A flash of electric blue—that's as intimately as most people will ever know the common kingfisher. But it suffices. . "Everyone in England who has ever seen one will remember where they saw it," says photographer and kingfisher thrall Charlie Hamilton James. "I saw my first one when I was a boy. I've been completely obsessed ever since." For a few years he traipsed empty-handed after the bird near Bristol, in southwest England. Later, to justify the hours spent on the gloomy riverbanks that king­fish­ers haunt, he took along a camera. That was 20 years ago.

Alcedo atthis (also known as the Eurasian, European, or river kingfisher) has inspired many an obsession. In the world's temperate zones, where drab plumage is the norm, this kingfisher, unlike its North American cousins, bedazzles. Slicing the air like a turquoise missile, it is impossible to disregard.

The yellow, red, orange, and brown birds of the world assume their hues because of a pigment embedded in the keratin matrix of feathers. But blue feathers result from refraction, a prism-style splitting of light inside a feather. Under a microscope each long kingfisher barb, finer than a human hair, glitters with shades of the Caribbean. Tiny structures in the feathers choreograph incoming light, reflecting sapphire in one direction, emerald in another.

Alas, beauty can be a curse. At times, kingfisher feathers have achieved the status of gemstones, silk, and spices. A third-century Chinese text describing Western cultures included a list of treasures that might be extracted from the Roman Empire: ivory, gold, carnelian, pearls, kingfisher feathers. Over the course of 2,500 years, the Chinese fashion industry plucked an inconceivable number of birds from the forests of Asia. In an art form called tian tsui, or dotting with kingfishers, craftsmen applied the shimmering feathers to jewelry, fans, privacy screens, and landscape panels. Entire quilts were reportedly transformed into blue-green seascapes. Korean royalty shared the passion, which finally faded in the early 1900s.

Fortunately, these days the little spitfire's rarity is an illusion. The kingfisher isn't shy; it simply exploits an environment most people (with the exception of Hamilton James and his sort) avoid. The ideal riverbank is crumbly enough for the birds to excavate a nesting burrow with their beaks. The nest should be sufficiently high to ride out occasional floods and sufficiently low to thwart foxes, snakes, and other raiders trying to penetrate from above.

Solitary most of the year, each individual strives to protect enough real estate to guarantee steady fishing and a good nest site. "These tiny little birds have got to hold down a whole mile of river," explains Hamilton James. Neither male nor female will hesitate in the defense of this life-sustaining territory. At just an ounce and a half, a kingfisher is a force to be reckoned with. "They're very loud, and they tell everyone they're coming," says Hamilton James. "I suppose they are quite arrogant."

Disputes begin with high-speed chases and the occasional beak jab. If aerial jousting doesn't settle the argument, things may turn deadly. At the river's edge two birds will lock beaks and attempt to force each other underwater.

Breeding season requires a pause in the usual hostilities between sexes. The male's opening move is direct: He hurtles after his former foe, whistling urgently. If she tolerates his company, he will ply her with fresh fish, directing them headfirst into her beak. On occasions when a truce is struck between neighbors, the pair will merge territories—temporarily. From their joint holdings they'll either select an old nest for reuse or start anew. Chiseling a two-foot tunnel can take ten days of hard labor for the pair.

After three weeks of brooding, the eggs hatch. Hardly fastidious homemakers, the birds raise their nestlings in the dark on a layer of tiny fish bones regurgitated as pellets, then shattered with a perfunctory peck. (Hamilton James has watched this behavior from a subterranean obser­vatory adjoining a nest.) Both parents fish in earnest. The kingfisher is an ambush hunter, perching over a river until a small fish flicks into range. It can plummet, strike, and wing back to its perch in the space of two blurry seconds. It thumps the catch against the branch to stun it—a lesson some young birds learn only after swallowing a stickleback that erects its dorsal spine on the way down. For the three or four weeks that chicks are in the nest, the adults may bring home 50 to 70 fish a day, and that messy layer of fish bones builds up.

What kingfishers lack in fine manners they make up for in fecundity. Many bird species will raise a second brood, but kingfishers, averaging six or seven eggs per clutch, often raise a third. One pair was observed raising a fourth.

Zealous reproduction helps the species thrive. Throughout its range, the kingfisher's status is stable enough that very few ornithologists pay it much heed. The handful of Alcedo atthis scholars report that it is one of the wild animals that don't mind rubbing shoulders with humans—good news in an increasingly urban world.

Hamilton James observes that his local birds are always willing to annex a backyard goldfish pond. And Japanese ornithologist Satoe Kasahara says that lately kingfishers have snatched fish from urban ponds in her country. Across the kingfisher's range, wherever rivers are healthy, fish will swim. And where the fish go, the flashy little bird with the sassy whistle is likely to follow.